Stanley Karnow, an author and journalist who wrote one of the seminal histories of the Vietnam War and won the Pulitzer Prize for his sweeping historical narrative of U.S. involvement in the Philippines, died Sunday at his home in Potomac, Md. He was 87.

He had congestive heart failure, said his son, Michael Karnow.

The New York-born Karnow launched his career as a foreign correspondent after setting sail for Europe on a coal freighter a week after graduating in 1947 from Harvard University. He subsequently became known for his distinguished coverage of the Vietnam War, first for Time magazine and later for news outlets that included the Saturday Evening Post, The Washington Post and NBC News.

Filing dispatches from the Far East for nearly 15 years — from the earliest days of American casualties in Vietnam — he became one of an elite handful of influential journalists who challenged the official stance in Washington that the United States was easily controlling the “struggle.”

His Emmy-winning, 13-part PBS series “Vietnam: A Television History” was one of the most widely viewed public-television documentaries ever when it first aired in 1983; his companion book, “Vietnam: A History,” sold millions of copies and was praised for its insight and comprehensiveness.

“In Our Image: America’s Empire in the Philippines,” the book for which he received the 1990 Pulitzer Prize in history, earned praise as the best popular history of America’s relationship with the Philippines. Karnow synthesized three centuries of Filipino foreign relations into what critics described as a compelling read, with vivid portraits of the Spanish, American and Filipino leaders who shaped the country that would be the United States’ only colony.

“It is hard to think of anyone in journalism who has done more, over a longer period, to help Americans understand East Asia,” said Donald Emmerson, a senior fellow at Stanford’s Institute for International Studies. In 2002, Karnow was the first recipient of the Shorenstein Award, a journalism prize given jointly by Harvard and Stanford universities to honor a body of work that illuminates coverage of Asia.

From his first stories out of post-World War II Paris, Karnow displayed a talent for aggressive reporting with vivid details and quotes. In Paris, he reported on the cultural and political figures who either lived in or passed through the City of Light — a breathless Audrey Hepburn at the beginning of her acting career, for instance, and an intoxicated Ernest Hemingway, who had just won the Nobel Prize for literature.

“Oh, that little Swedish thing,” Karnow quoted him as saying. “Gave it to the mayor of Havana.”

In 1959, he was sent by Time magazine to the British colony of Hong Kong. No Americans were allowed into China, so Karnow and other foreign correspondents watched from afar and wrote about what other outsiders were speculating.

Karnow called Hong Kong at the time a “sleepy colonial backwater”; he had enough time to try to help a local restaurant learn how to serve Jewish deli food, he later recalled wryly. The failed venture, he said in speeches, showed how little he knew about the region he was supposed to be explaining to the Western world.

Vietnam changed the timbre of his job. Karnow wrote that he had no idea what was coming when he filed a story in 1959 about two American soldiers killed in Bien Hoa in July 1959 — the first U.S. military casualties in what would become known as the “Vietnam Era.”

“My dispatch about the incident at Bien Hoa earned only a modest amount of space in Time magazine — it deserved no more,” he wrote in “Vietnam: A History.” “For nobody could have imagined then that some three million Americans would serve in Vietnam — or that nearly fifty-eight thousand were to perish in its jungles and rice fields. . . . Nor did I then, surveying the bullet-pocked villa at Bien Hoa, even remotely envision the holocaust that would devastate Vietnam during the subsequent sixteen years of war.”

Within a few years, Karnow came to believe that the conflict in Vietnam would be one of the United States’ most critical international concerns. When he pressed Kennedy administration officials on this during a trip back to Washington in 1961, then-Attorney General Robert Kennedy snapped back at him, “Vietnam? We’ve got 20 Vietnams a day.” Later, his persistent critiques of the war earned him a spot on President Richard Nixon’s enemies list — something Karnow called, half jokingly, “one of the highlights of my life.”

“Stanley did not accept the official version of the war in 1962 and ’63,” recalled Pulitzer Prize-winning author Neil Sheehan, who was the United Press International bureau chief in Saigon at the time. Sheehan said Karnow often stopped by the office Sheehan shared with then-New York Times reporter David Halberstam and read the carbon copies of their daily reports.

“He didn’t waste time rewriting what we had already written,” said Sheehan, author of the acclaimed Vietnam War book “A Bright Shining Lie.” “He took off from that and did an analytical piece. That was shrewd journalism — don’t waste your opportunities regurgitating what someone else has already written; write something fresh.”

Karnow’s impact came from the long-term breadth and depth of his work, which Emmerson said was infused with “respect for complexity, aversion to cant and enthusiasm for context.”

Although he expressed pride when his colleagues labeled him an “old school journalist” — the sort of foreign correspondent who wore a jacket and tie even in the tropics, who always had a pack of Gitanes cigarettes on hand — Karnow acknowledged that by the middle of his career he had stepped away from the reporter’s lifestyle.

“Good reporters are perennial adolescents — restless, skeptical, petulant, compulsively inquisitive,” he wrote in The Washington Post in 1998, explaining his transition to book writing. “I adored every minute of it until I reached my mid-40s. By that point, I had been rushing around Europe, Africa and Asia on suitcase assignments for years. My legs were giving out. Rather than retire to a university or a golf course, I began to ponder the idea of shifting to a career in books.”

Karnow had received an Overseas Press Club award for a series of articles in The Post leading up to the 20th anniversary of the 1949 Communist takeover of China. His most prominent early book was “Mao and China: From Revolution to Revolution,” published in 1972 and later revised and updated.

For all his travels, he once said, Asia was the region that most fascinated him because it appealed to his scholarly nature. “Asia gets into your blood, your psyche,” he told a Stanford interviewer. “It was a perpetual excitement about its diversity” of regional languages and dialects, of cultural traditions and of constantly shifting political developments.

When covering Asia, he said, “you can be a specialist, but not an expert.”

Stanley Abram Karnow was born Feb. 4, 1925, in Brooklyn, N.Y. His father was a machinery salesman. His mother, a Hungarian immigrant, was a homemaker.

“I was a typical Jewish kid in a lace-curtained, cloistered environment,” he told The Washington Post in 1998. “It didn’t take long for me to realize I wanted out.”

After he received a portable typewriter for his bar mitzvah, he began writing almost every day; he devoured books and articles about faraway places. Reading the memoir of globetrotting reporter Vincent Sheean set him on the path to journalism. He became the sports editor of his high school newspaper and an editorial and feature writer for the Harvard Crimson newspaper.

Karnow left college during World War II and served in the Army Air Forces in the mountains between China and India as a weather observer, cryptographer and unit historian. He said he didn’t hear one shot fired.

After Harvard, he left for Paris with a friend from the Crimson, the future New York Times columnist Anthony Lewis. Karnow intended to spend a week but instead remained for a decade. He used his G.I. Bill money to enroll at the Sorbonne and at the Ecole des Sciences Politiques and supported himself by finding work as a gofer in Time’s Paris bureau in 1950.

Meanwhile, he said he “plunged” into the city. He married Claude Sarraute, whose Russian-Jewish family was part of the Parisian literary scene, and hobnobbed with other expatriate Americans who, he said, “were riding the GI Bill and studying — or pretending to study — such subjects as art, literature, ballet, even haute cuisine. . . . Many of us had ambitious plans, but life at the time was too leisurely and pleasant to fuss about them.”

He gradually moved up the ranks to be a Time correspondent. Karnow was bureau chief in North Africa from 1958 to 1959 and then in Hong Kong until 1962. After two years with the Saturday Evening Post, he worked for The Washington Post as a Far East correspondent from 1965 to 1971, then briefly as a diplomatic correspondent before serving a stint with NBC.

Over the years, he also was a columnist for Newsweek and the London Observer, a correspondent for public television, and a syndicated columnist with King Features and other agencies. He continued writing until his death, spending hours in his Potomac home’s basement office, which he jokingly referred to as “Santa’s Work Shop.”

His first marriage ended in divorce. In 1959, he married Annette Kline, an artist who was working at the time as cultural attache for the U.S. State Department in Algiers. She died in 2009.

Survivors include two children from his second marriage, Catherine Karnow of Mill Valley, Calif., and Michael Karnow of Venice, Calif.; a stepson he adopted, Curtis E. Karnow of San Rafael, Calif.; and two grandchildren.

Despite having been thrilled to work as a foreign correspondent for Time, Karnow showed a wry lack of reverence for its publisher, Henry Luce. Karnow once told the story of retrieving Luce at the airport in Taiwan, where Nationalist leader Chiang Kai-shek had fled after the Communist victory.

“I think they’ve lost our bags,” Karnow said on the way to the hotel. “It won’t be the first thing they’ve lost.”

The publisher, a major supporter of the Nationalist cause, was livid at the remark.

“Within a year,” Karnow told author Sterling Seagrave, “I was no longer working for Time.”